Volume Maps Research Articles

Cardiac Magnetic Resonance-Derived Extracellular Volume Mapping for the Quantification of Hepatic and Splenic Amyloid.

Systemic amyloidosis is characterized by amyloid deposition that can involve virtually any organ. Splenic and hepatic amyloidosis occurs in certain types, in some patients but not others, and may influence prognosis and treatment. SAP (serum amyloid P component) scintigraphy is uniquely able to identify and quantify amyloid in the liver and spleen, thus informing clinical management, but it is only available in 2 centers globally. The aims of this study were to examine the potential for extracellular volume (ECV) mapping performed during routine cardiac magnetic resonance to: (1) detect amyloid in the liver and spleen and (2) estimate amyloid load in these sites using SAP scintigraphy as the reference standard. Five hundred thirty-three patients referred to the National Amyloidosis Centre, London, between 2015 and 2017 with suspected systemic amyloidosis who underwent SAP scintigraphy and cardiac magnetic resonance with T1 mapping were studied. The diagnostic performance of ECV to detect splenic and hepatic amyloidosis was high for both organs (liver: area under the curve, -0.917 [95% CI, 0.880-0.954]; liver ECV cutoff, 0.395; sensitivity, 90.7%; specificity, 77.7%; P<0.001; spleen: area under the curve, -0.944 [95% CI, 0.925-0.964]; spleen ECV cutoff, 0.385; sensitivity, 93.6%; specificity, 87.5%; P<0.001). There was good correlation between liver and spleen ECV and amyloid load assessed by SAP scintigraphy (r=0.504, P<0.001; r=0.693, P<0.001, respectively). There was high interobserver agreement for both the liver and spleen (ECV liver intraclass correlation coefficient, 0.991 [95% CI, 0.984-0.995]; P<0.001; ECV spleen intraclass correlation coefficient, 0.995 [95% CI, 0.991-0.997]; P<0.001) with little bias across a wide range of ECV values. Our study demonstrates that ECV measurements obtained during routine cardiac magnetic resonance scans in patients with suspected amyloidosis can identify and measure the magnitude of amyloid infiltration in the liver and spleen, providing important clues to amyloid type and offering a noninvasive measure of visceral amyloid burden that can help guide and track treatment.

Malang coffee value chain analysis: A case study of Taji arabica coffee

Taji is a coffee-producing area in Malang Regency, East Java, Indonesia. This study aims to analyze the coffee value chain produced by Taji villages that are distributed to cafes in Malang City. The study was conducted in Taji Village, Malang Regency and Angkot Café, Malang City. Value chain analysis is performed using the Hayami method. This study obtained actors, volume, and value mapping of Taji coffee. There are four main actors involved in the Taji arabica coffee value chain: the farmers, the collector, the first-stage processor, and the second-stage processor. The mapping of the value offered for every kilogram output received by farmers is IDR 7,000, the collector is IDR 10,000, the first stage processor is IDR 90,000, and the second-stage processor is IDR 220,000. The second-stage processor obtained the highest margin with the amount of IDR 99,239. All actors receive satisfactory margins.

Optimizing the diagnosis and assessment of chronic thromboembolic pulmonary hypertension with advancing imaging modalities.

Imaging is key to nearly all aspects of chronic thromboembolic pulmonary hypertension including management for screening, assessing eligibility for pulmonary endarterectomy, and post-operative follow-up. While ventilation/perfusion scintigraphy, the gold standard technique for chronic thromboembolic pulmonary hypertension screening, can have excellent sensitivity, it can be confounded by other etiologies of pulmonary malperfusion, and does not provide structural information to guide operability assessment. Conventional computed tomography pulmonary angiography has high specificity, though findings of chronic thromboembolic pulmonary hypertension can be visually subtle and unrecognized. In addition, computed tomography pulmonary angiography can provide morphologic information to aid in pre-operative workup and assessment of other structural abnormalities. Advances in computed tomography imaging techniques, including dual-energy computed tomography and spectral-detector computed tomography, allow for improved sensitivity and specificity in detecting chronic thromboembolic pulmonary hypertension, comparable to that of ventilation/perfusion scans. Furthermore, these advanced computed tomography techniques, compared with conventional computed tomography, provide additional physiologic data from perfused blood volume maps and improved resolution to better visualize distal chronic thromboembolic pulmonary hypertension, an important consideration for balloon pulmonary angioplasty for inoperable patients. Electrocardiogram-synchronized techniques in electrocardiogram-gated computed tomography can also show further information regarding right ventricular function and structure. While the standard of care in the workup of chronic thromboembolic pulmonary hypertension includes a ventilation/perfusion scan, computed tomography pulmonary angiography, direct catheter angiography, echocardiogram, and coronary angiogram, in the future an electrocardiogram-gated dual-energy computed tomography angiography scan may enable a “one-stop” imaging study to guide diagnosis, operability assessment, and treatment decisions with less radiation exposure and cost than traditional chronic thromboembolic pulmonary hypertension imaging modalities.

Improved estimation of forest stand volume by the integration of GEDI LiDAR data and multi-sensor imagery in the Changbai Mountains Mixed forests Ecoregion (CMMFE), northeast China

Forest stand volume is a vital indicator of productivity and carbon storage. Conventionally, stand volume is estimated from field samples, Synthetic Aperture Radar (SAR), and optical imagery, which suffer saturation problems. Although Light Detection and Ranging (LiDAR) technique degrades the signal saturation, its large-scale application is hindered by spatial continuity. To address this issue, recently released Global Ecosystem Dynamics Investigation (GEDI) LiDAR data, Sentinel-1 SAR, Sentinel-2 Multispectral Instrument (MSI), and Advanced Land Observing Satellite (ALOS) digital surface model (DSM) imagery were integrated for volume modeling and estimation under a point-line-polygon framework. The footprint-level LiDAR variables, as a linear bridge, were adopted to link field plots to the full-cover multi-sensor imagery. Results showed that volume of the Changbai Mountains Mixed Forests Ecoregion (CMMFE) displayed variations along the elevation gradient, ranging from 47.56 to 277.30 m3/ha with a mean value of 151.39 m3/ha. Additionally, the accuracy comparison based on independent validation samples indicated that integrating GEDI LiDAR data under a point-line-polygon framework performed better than the traditional point-polygon approach, which directly linked field samples to multi-sensor imagery. The corresponding estimated error declined from 22.08% to 15.21%. The canopy cover and tree height from LiDAR, elevation from L band InSAR, and spectral indices of MSI red-edge bands were key for stand volume mapping in heterogeneous temperate forests. This comparison also showed that the integration of LiDAR by a point-line-polygon framework adopted 2/3 of the modeling points but acquired more accurate estimation than a traditional approach only based on multi-sensor imagery, which implied less field sampling work was needed for similar research. Consequently, as a pioneering exploration of GEDI LiDAR data combined with multi-sensor imagery under the point-line-polygon framework, this study provides an efficient methodology for the volume estimation of heterogeneous forests.

Dual-energy CT evidence of pulmonary microvascular occlusion in patients with sickle cell disease experiencing acute chest syndrome

PurposeAcute chest syndrome (ACS), defined by the presence of a chest radiographic opacity in sickle cell disease patients experiencing respiratory symptoms is a leading cause of death in these patients. The etiology is ACS is not well understood however pulmonary microvascular occlusion has been postulated to be a major pathophysiologic driver. Our study aims to assess the value of dual-energy CT (DECT) as a marker of pulmonary microvascular occlusion. Materials/methodsA search tool was used to identify CT angiography studies from 1/1/2017 to 9/15/2019 with any variation of the phrases “Acute chest syndrome” and “Sickle cell”. These studies were manually reviewed for the use of DECT technique. An age-matched control group was created. DECT pulmonary blood volume (PBV) maps were reviewed semi-quantitatively for the presence of iodine defects and the number of involved bronchopulmonary segments were scored. Other recorded values included type of parenchymal opacities, diameter of main pulmonary artery (MPA) and presence of right ventricular dilatation. Mean values between cases and controls were compared using a two-sample t-test. ResultsNine sickle cell DECT cases with PBV maps and nine age-matched controls were evaluated. Bronchopulmonary segments with iodine defects were significantly higher in cases vs controls (mean: 4.7 vs 0.3, p < 0.003). PBV defects were more extensive than parenchymal findings. MPA diameter was higher in cases (2.9 cm) vs control (2.4 cm), P < 0.03. ConclusionsDECT demonstrates abnormal PBV in sickle cell patients, often the predominant abnormality identified early, and likely reflects the presence of pulmonary microvascular occlusion.

Differentiating IDH status in human gliomas using machine learning and multiparametric MR/PET

BackgroundThe purpose of this study was to develop a voxel-wise clustering method of multiparametric magnetic resonance imaging (MRI) and 3,4-dihydroxy-6-[18F]-fluoro-L-phenylalanine (FDOPA) positron emission tomography (PET) images using an unsupervised, two-level clustering approach followed by support vector machine in order to classify the isocitrate dehydrogenase (IDH) status of gliomas.MethodsSixty-two treatment-naïve glioma patients who underwent FDOPA PET and MRI were retrospectively included. Contrast enhanced T1-weighted images, T2-weighted images, fluid-attenuated inversion recovery images, apparent diffusion coefficient maps, and relative cerebral blood volume maps, and FDOPA PET images were used for voxel-wise feature extraction. An unsupervised two-level clustering approach, including a self-organizing map followed by the K-means algorithm was used, and each class label was applied to the original images. The logarithmic ratio of labels in each class within tumor regions was applied to a support vector machine to differentiate IDH mutation status. The area under the curve (AUC) of receiver operating characteristic curves, accuracy, and F1-socore were calculated and used as metrics for performance.ResultsThe associations of multiparametric imaging values in each cluster were successfully visualized. Multiparametric images with 16-class clustering revealed the highest classification performance to differentiate IDH status with the AUC, accuracy, and F1-score of 0.81, 0.76, and 0.76, respectively.ConclusionsMachine learning using an unsupervised two-level clustering approach followed by a support vector machine classified the IDH mutation status of gliomas, and visualized voxel-wise features from multiparametric MRI and FDOPA PET images. Unsupervised clustered features may improve the understanding of prioritizing multiparametric imaging for classifying IDH status.

Minute changes of cerebral parenchymal non-contrast computed tomography attenuation reflect cerebral volume alterations of blood.

Non-infarcted acute cerebral ischaemic areas appear hypo-attenuated on non-contrast narrow-window computed tomography images. We aimed to determine the mechanism underlying minute computed tomography hypo-attenuation and visualise these attenuation changes on non-contrast computed tomography images. The cerebral parenchyma was defined by pixels with attenuation of 20-50 Hounsfield units. We calculated the mean cerebral parenchymal attenuation in non-contrast computed tomography images. We analysed the correlation of complete blood counts with corresponding mean cerebral parenchymal attenuation values using linear regression analysis. Moreover, we developed an image processing method that involved pixel colorisation based on the noise-reduced attenuation value for minute cerebral parenchymal attenuation visualisation. Haemoglobin, haematocrit and red blood cell counts positively correlated with mean cerebral parenchymal attenuation values. The cerebral haematocrit is correlated with the blood haematocrit; therefore, cerebral parenchymal attenuation correlated linearly with cerebral haemoglobin concentration. Haemoglobin contents in a pixel partially determine the X-ray absorption dose and attenuation value. Pixel haemoglobin contents are determined by the cerebral volume of blood in a pixel. Image processed computed tomography images reflected cerebral volume of blood and showed the same alterations with regional cerebral blood volume maps of perfusion computed tomography. Cerebral parenchymal attenuation correlated with cerebral haemoglobin concentration and cerebral volume of blood. Infarcted cerebral parenchyma shows about 5 Hounsfield units gray matter attenuation decrease. Attenuation decrease by less than 5 Hounsfield units means decreased cerebral volume of blood, indicating a reversible functional change. One cannot recognise minute hypo-attenuation (<5 Hounsfield units) in routine computed tomography images. However, it can be visualised through an image processing method on non-contrast computed tomography images. It may detect pre-infarction cerebral volume of blood and regional cerebral blood volume alterations.

Multi-parametric cardiovascular magnetic resonance with regadenoson stress perfusion is safe following pediatric heart transplantation and identifies history of rejection and cardiac allograft vasculopathy

BackgroundThe progressive risk of graft failure in pediatric heart transplantation (PHT) necessitates close surveillance for rejection and coronary allograft vasculopathy (CAV). The current gold standard of surveillance via invasive coronary angiography is costly, imperfect and associated with complications. Our goal was to assess the safety and feasibility of a comprehensive multi-parametric CMR protocol with regadenoson stress perfusion in PHT and evaluate for associations with clinical history of rejection and CAV.MethodsWe performed a retrospective review of 26 PHT recipients who underwent stress CMR with tissue characterization and compared with 18 age-matched healthy controls. CMR protocol included myocardial T2, T1 and extracellular volume (ECV) mapping, late gadolinium enhancement (LGE), qualitative and semi-quantitative stress perfusion (myocardial perfusion reserve index; MPRI) and strain imaging. Clinical, demographics, rejection score and CAV history were recorded and correlated with CMR parameters.ResultsMean age at transplant was 9.3 ± 5.5 years and median duration since transplant was 5.1 years (IQR 7.5 years). One patient had active rejection at the time of CMR, 11/26 (42%) had CAV 1 and 1/26 (4%) had CAV 2. Biventricular volumes were smaller and cardiac output higher in PHT vs. healthy controls. Global T1 (1053 ± 42 ms vs 986 ± 42 ms; p < 0.001) and ECV (26.5 ± 4.0% vs 24.0 ± 2.7%; p = 0.017) were higher in PHT compared to helathy controls. Significant relationships between changes in myocardial tissue structure and function were noted in PHT: increased T2 correlated with reduced LVEF (r = − 0.57, p = 0.005), reduced global circumferential strain (r = − 0.73, p < 0.001) and reduced global longitudinal strain (r = − 0.49, p = 0.03). In addition, significant relationships were noted between higher rejection score and global T1 (r = 0.38, p = 0.05), T2 (r = 0.39, p = 0.058) and ECV (r = 0.68, p < 0.001). The presence of even low-grade CAV was associated with higher global T1, global ECV and maximum segmental T2. No major side effects were noted with stress testing. MPRI was analyzed with good interobserver reliability and was lower in PHT compared to healthy controls (0.69 ± − 0.21 vs 0.94 ± 0.22; p < 0.001).ConclusionIn a PHT population with low incidence of rejection or high-grade CAV, CMR demonstrates important differences in myocardial structure, function and perfusion compared to age-matched healthy controls. Regadenoson stress perfusion CMR could be safely and reliably performed. Increasing T2 values were associated with worsening left ventricular function and increasing T1/ECV values were associated with rejection history and low-grade CAV. These findings warrant larger prospective studies to further define the role of CMR in PHT graft surveillance.

Atomistic insight towards the impact of polymer architecture and grafting density on structure-dynamics of PEGylated bovine serum albumin and their applications.

Macromolecules such as proteins conjugated to polyethylene glycol (PEG) have been employed in therapeutic drug applications, and recent research has emphasized the potential of varying polymer architectures and conjugation strategies to achieve improved efficacy. In this study, we performed atomistic molecular dynamics simulations of bovine serum albumin (BSA) conjugated to 5 kDa PEG polymers in an array of schemes, including varied numbers of attached chains, grafting density, and nonlinear architectures. Nonlinear architectures included U-shaped PEG, Y-shaped PEG, and poly(oligoethylene glycol methacrylate) (POEGMA). Buried surface area calculations and polymer volume map analyses revealed that volume exclusion behaviors of the high grafting density conjugate promoted additional protein-polymer interactions when compared to simply increasing numbers of conjugated chains uniformly across the protein surface. Investigation of nonlinear polymer architectures showed that stable polymer-lysine loop-like conformations seen in previous conjugate designs were more variable in prevalence, especially in POEGMA, which contained short oligomer PEG chains. The findings of this comprehensive study of alternate PEGylation schemes of BSA provide critical insight into molecular patterns of interaction within bioconjugates and highlight their importance in the future of controlled modification of conjugate system parameters.

Investigation of convolutional neural networks using multiple computed tomography perfusion maps to identify infarct core in acute ischemic stroke patients.

Purpose: To assess acute ischemic stroke (AIS) severity, infarct is segmented using computed tomography perfusion (CTP) software, such as RAPID, Sphere, and Vitrea, relying on contralateral hemisphere thresholds. Since this approach is potentially patient dependent, we investigated whether convolutional neural networks (CNNs) could achieve better performances without the need for contralateral hemisphere thresholds. Approach: CTP and diffusion-weighted imaging (DWI) data were retrospectively collected for 63 AIS patients. Cerebral blood flow (CBF), cerebral blood volume (CBV), time-to-peak, mean-transit-time (MTT), and delay time maps were generated using Vitrea CTP software. U-net shaped CNNs were developed, trained, and tested for 26 different input CTP parameter combinations. Infarct labels were segmented from DWI volumes registered with CTP volumes. Infarct volumes were reconstructed from two-dimensional CTP infarct segmentations. To remove erroneous segmentations, conditional random field (CRF) postprocessing was applied and compared with prior results. Spatial and volumetric infarct agreement was assessed between DWI and CTP (CNNs and commercial software) using median infarct difference, median absolute error, dice coefficient, positive predictive value. Results: The most accurate combination of parameters for CNN segmenting infarct using CRF postprocessing was CBF, CBV, and MTT (4.83mL, 10.14mL, 0.66, 0.73). Commercial software results are: RAPID = (2.25mL, 21.48mL, 0.63, 0.70), Sphere = (7.57mL, 17.74mL, 0.64, 0.70), Vitrea = (6.79mL, 15.28mL, 0.63, 0.72). Conclusions: Use of CNNs with multiple input perfusion parameters has shown to be accurate in segmenting infarcts and has the ability to improve clinical workflow by eliminating the need for contralateral hemisphere comparisons.

Brain Structural Changes in Patients with Pulmonary Arterial Hypertension.

Patients with pulmonary arterial hypertension (PAH) frequently present with anxiety, depression, autonomic, and cognitive deterioration, which may indicate brain changes in regions that control these functions. However, the precise regional brain-injury in sites that regulate cognitive, autonomic, and mood functions in PAH remains unclear. We examined the shifts in regional gray matter (GM) volume, using high-resolution T1-weighted images, and brain tissue alterations, using T2-relaxometry procedures, in PAH compared to healthy subjects. We collected two high-resolution T1-weighted series, and proton-density and T2-weighted images using a 3.0-Tesla magnetic resonance imaging scanner from 9 PAH and 19 healthy subjects. Both high-resolution T1-weighted images were realigned and averaged, partitioned to GM tissue type, normalized to a common space, and smoothed. Using proton-density and T2-weighted images, T2-relaxation maps were calculated, normalized to a common space, and smoothed. Whole-brain GM volume and T2-relaxation maps were compared between PAH and controls using analysis of covariance (covariates, age, sex, and total-brain-volume; false discover rate corrections). Significantly decreased GM volumes, indicating tissue injury, emerged in multiple brain regions, including the hippocampus, insula, cerebellum, parahippocampus, temporal, frontal, and occipital gyri, cingulate, amygdala, and thalamus. Higher T2-relaxation values, suggesting tissue damage, appeared in the cerebellum, hippocampus, parahippocampus, frontal, lingual, and temporal and occipital gyri, and cingulate areas in PAH compared to healthy subjects. PAH patients showed significant GM injury and brain tissue changes in sites that regulate cognition, autonomic, and mood functions. These findings indicate a brain structural basis for functional deficits in PAH patients.

Cardiovascular magnetic resonance imaging reveals asymptomatic cardiomyopathy in newly diagnosed, HIV-infected South African adults

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): University of Stellenbosch Cardiology Research Fund and United States National Institutes of Health/Fogarty International Center Background Cardiovascular disease (CVD) is a leading cause of death and disability in people living with HIV (PLWH). The coronary disease burden in high income countries contrast what is experienced in low- and middle-income countries where cardiomyopathy remains prevalent. Cardiovascular magnetic resonance imaging (CMR) has the unique ability to characterise tissues to obtain "virtual histology". Our data support a high burden of myocardial disease, already present at the time of HIV diagnosis in a young South African cohort. Purpose Early, undiagnosed myocardial pathology in some antiretroviral therapy (ART) naïve persons appear to precede the development of poorly prognostic HIV associated cardiomyopathy. The burden and mechanisms underlying the progression to more advanced disease in treatment naïve PLWH remain largely unknown, as does the modifying effect of ART on these abnormalities. Studying early myocardial disease and its progression with serial CMR evaluation will improve our understanding of disease evolution. Methods 24 newly diagnosed, ART naïve adults without known CVD underwent a contrasted, 1.5T CMR study. Assessments included: Left ventricular (LV) volumes, mass, ejection fraction (EF), native and post-contrast T1 mapping, T2 mapping, extracellular volume (ECV) mapping, and late gadolinium enhancement (LGE) imaging. Quantitative measurements were obtained using a semi-automated software. Qualitative LGE findings were reviewed by an EACVI level III accredited cardiologist. Results The median age of the cohort was 33, interquartile range (IQR) 30-43 years. Median CD4 count was 250, IQR 152-520 cells/uL. All patients had non-dilated LV"s according to indexed end diastolic volumes (Mean: 85 ± 15ml/m²). No patient had overt systolic dysfunction (Mean EF: 62 ± 6%). Non-trivial pericardial effusions were present in 71% of cases. Indexed LV mass measured normal (Mean: 65 ± 12g/m²). Mean global native T1 and T2 values were 1043 ± 46 and 49 ± 4ms respectively. Native T1 values were highest in the septum and inferior wall (Mean: 1054 ± 50 and 1047 ± 51ms respectively). Mean global ECV was 28 ± 4%. Non-ischaemic LGE was present in 71% of participants. In those with LGE, midmyocardial enhancement of the inferior septum represented 71% of abnormalities (Figure). Conclusion In this young cohort of newly diagnosed HIV-infected persons, the prevalence of myocardial abnormalities were high. The midmyocardial LGE and abnormal mapping parameters (high for our scanner and high normal for published data) suggest myocardial inflammation and fibrosis already present at HIV-diagnosis. This was most appreciable in the septum and inferior walls, and likely represents a diffuse process that may progress to symptomatic cardiomyopathy over time. Serial evaluation on ART and comparison with a matched HIV-negative control group is planned. This will allow quantitative comparison of tissue characterisation and explore the nature and evolution of these abnormalities. Abstract Figure. Late gadolinium enhancement (Arrows)

Cardiovascular Magnetic Resonance Mapping and Strain Assessment for the Diagnosis of Cardiac Involvement in Idiopathic Inflammatory Myopathy Patients With Preserved Left Ventricular Ejection Fraction.

The aim of the study was to evaluate the role of cardiac magnetic resonance (CMR) mapping and strain analysis in the identification of cardiac involvement in idiopathic inflammatory myopathy (IIM) patients with preserved left ventricular ejection fraction. In all, 38 IIM patients who underwent CMR examination at our institution were retrospectively included. Twenty-three age-matched healthy individuals served as controls. Mapping parameters including native T1, extracellular volume (ECV), and T2 mapping and strain parameters including global radial strain, global circumferential strain, and global longitudinal strain were measured semiautomatically using a dedicated processing software. All the mapping and strain values were compared between patients and controls. Late gadolinium enhancement was only present in IIM patients (n=17, 44.7%). IIM patients showed higher native T1 (1346 vs. 1269 ms, P<0.001), ECV (31.1% vs. 27.4%, P<0.01), and higher T2 (44.4 vs. 39.2 ms, P<0.001) values compared with controls. The global radial strain (36.7% vs. 46.9%, P<0.001), global circumferential strain (-21.2% vs. -24.1%, P<0.01), and global longitudinal strain (-13.6% vs. -15.6%, P<0.05) values were significantly reduced compared with controls. Native T1, ECV, T2 values, and global strain values may hold promise for the detection of subclinical myocardial involvement in IIM patients with preserved left ventricular ejection fraction.

3D characterization of low optical absorption structures in large crystalline sapphire substrates for gravitational wave detectors

Very high-quality sapphire substrates are key elements of the cryogenic Japanese gravitational interferometer KAGRA, in which they are used to build the main mirrors, working as the test masses to sense the gravitational waves. To meet the extreme requirements of this system, the sapphire test masses must possess an extremely low optical absorption, which makes their study challenging using standard methods. In this paper, we illustrate the results obtained on two typical samples using a specialized absorption setup based on the technique of Photo-thermal Common-path Interferometry (PCI). Our system combines a very high sensitivity to small absorption features with the possibility to perform a full three-dimensional mapping of the sample volume. Our results elucidate how the ultra-low absorption variations inside the sample possess a structure that is probably inherited from the growth history of the sample. Some conclusions on the role of structural defects as preferential sites for the inclusion of absorbing centers are drawn.

Obesity and Brain Vulnerability in Normal and Abnormal Aging: A Multimodal MRI Study.

Background: How the relationship between obesity and MRI-defined neural properties varies across distinct stages of cognitive impairment due to Alzheimer’s disease is unclear.Objective: We used multimodal neuroimaging to clarify this relationship.Methods: Scans were acquired from 47 patients clinically diagnosed with mild Alzheimer’s disease dementia, 68 patients with mild cognitive impairment, and 57 cognitively healthy individuals. Voxel-wise associations were run between maps of gray matter volume, white matter integrity, and cerebral blood flow, and global/visceral obesity.Results: Negative associations were found in cognitively healthy individuals between obesity and white matter integrity and cerebral blood flow of temporo-parietal regions. In mild cognitive impairment, negative associations emerged in frontal, temporal, and brainstem regions. In mild dementia, a positive association was found between obesity and gray matter volume around the right temporoparietal junction.Conclusion: Obesity might contribute toward neural tissue vulnerability in cognitively healthy individuals and mild cognitive impairment, while a healthy weight in mild Alzheimer’s disease dementia could help preserve brain structure in the presence of age and disease-related weight loss.

Structural Imaging-Based Biomarkers for Detecting Craving and Predicting Relapse in Subjects With Methamphetamine Dependence.

Background: Craving is the predictor of relapse, and insula cortex (IC) is a critical neural substrate for craving and drug seeking. This study investigated whether IC abnormalities among MA users can detect craving state and predict relapse susceptibility.Methods: A total of 142 subjects with a history of MA dependence completed structural MRI (sMRI) scans, and 30 subjects (10 subjects relapsed) completed 4-month follow-up scans. MA craving was measured by the Visual Analog Scale for Craving. Abnormalities of IC gray matter volume (GMV) between the subjects with and without craving were investigated by voxel-based morphometry (VBM). The receiver operating characteristic (ROC) analysis was performed for the region-of-interest (ROI) of IC GMV to assess the diagnostic accuracy.Results: By comparing whole-brain volume maps, this study found that subjects without craving (n = 64) had a significantly extensive decrease in IC GMV (family-wise error correction, p < 0.05) than subjects with craving group (n = 78). The ROI of IC GMV had a significantly positive correlation with the craving scores reported by MA users. The ROC analysis showed a good discrimination (area under curve is 0.82/0.80 left/right) for IC GMV between the subjects with and without craving. By selecting Youden index cut-off point from whole model group, calculated sensitivity/specificity was equal to 78/70% and 70/75% for left and right IC, respectively. By applying the above optimal cut-off values to 30 follow-up subjects as validations, the results showed a similar sensitivity (73–80%) and specificity (73–80%) for detecting craving state as model group. For predicting relapse susceptibility, the sensitivity (50–55%) was low and the specificity (80–90%) was high.Conclusions: Our study provides the first evidence that sMRI may be used to diagnosis the craving state in MA users based on optimal cut-off values, which could be served as MRI bio-markers and an objective measure of craving state.

Quantitative assessment of pulmonary artery occlusion using lung dynamic perfusion CT

Quantitative measurement of lung perfusion is a promising tool to evaluate lung pathophysiology as well as to assess disease severity and monitor treatment. However, this novel technique has not been adopted clinically due to various technical and physiological challenges; and it is still in the early developmental phase where the correlation between lung pathophysiology and perfusion maps is being explored. The purpose of this research work is to quantify the impact of pulmonary artery occlusion on lung perfusion indices using lung dynamic perfusion CT (DPCT). We performed Lung DPCT in ten anesthetized, mechanically ventilated juvenile pigs (18.6–20.2 kg) with a range of reversible pulmonary artery occlusions (0%, 40–59%, 60–79%, 80–99%, and 100%) created with a balloon catheter. For each arterial occlusion, DPCT data was analyzed using first-pass kinetics to derive blood flow (BF), blood volume (BV) and mean transit time (MTT) perfusion maps. Two radiologists qualitatively assessed perfusion maps for the presence or absence of perfusion defects. Perfusion maps were also analyzed quantitatively using a linear segmented mixed model to determine the thresholds of arterial occlusion associated with perfusion derangement. Inter-observer agreement was assessed using Kappa statistics. Correlation between arterial occlusion and perfusion indices was evaluated using the Spearman-rank correlation coefficient. Our results determined that perfusion defects were detected qualitatively in BF, BV and MTT perfusion maps for occlusions larger than 55%, 80% and 55% respectively. Inter-observer agreement was very good with Kappa scores > 0.92. Quantitative analysis of the perfusion maps determined the arterial occlusion threshold for perfusion defects was 50%, 76% and 44% for BF, BV and MTT respectively. Spearman-rank correlation coefficients between arterial occlusion and normalized perfusion values were strong (− 0.92, − 0.72, and 0.78 for BF, BV and MTT, respectively) and were statically significant (p < 0.01). These findings demonstrate that lung DPCT enables quantification and stratification of pulmonary artery occlusion into three categories: mild, moderate and severe. Severe (occlusion ≥ 80%) alters all perfusion indices; mild (occlusion < 55%) has no detectable effect. Moderate (occlusion 55–80%) impacts BF and MTT but BV is preserved.

Quantitative and qualitative application of clinical drawings for image-guided brachytherapy in cervical cancer patients.

PurposeClinical drawings are integral part of image-guided adaptive brachytherapy (IGABT) of cervical cancer. It was used in EMBRACE study protocol as a useful tool. In our study clinical drawings from EMBRACE study were modified to include scales in all the dimensions for more accurate representation of various tumor related volumes. The aim of the present study was to understand patterns of tumor regression and relationship between gross tumor at diagnosis (GTVD) and high-risk clinical target volume (CTV-THR)/intermediate-risk clinical target volume (CTV-TIR) in brachytherapy (BRT), using modified clinical drawings.Material and methods42 cervical cancer patients, staged as FIGO IIB-IIIB according to EMBRACE study, were enrolled. Advanced schematic 3D mapping diagram (3D-MD) in axial, coronal, and sagittal orientations, with a measurement scale (grid with 10 mm distance) for precise assessment and documentation was applied (through MRI at diagnosis and during brachytherapy). Dimensions, including height, width, and thickness as well as volumes (GTVD, CTV-THR and CTV-TIR) were compared both qualitatively and quantitatively.Results and conclusionsWe found qualitative and quantitative correlation of the dimensions of final CTV-THR with initial GTVD. Meticulous mapping of tumor volumes can provide useful insights to CTV-THR volume during brachytherapy.

Fluorine (19F) MRI to Measure Renal Oxygen Tension and Blood Volume: Experimental Protocol.

Fluorinated compounds feature favorable toxicity profile and can be used as a contrast agent for magnetic resonance imaging and spectroscopy. Fluorine nucleus from fluorinated compounds exhibit well-known advantages of being a high signal nucleus with a natural abundance of its stable isotope, a convenient gyromagnetic ratio close to that of protons, and a unique spectral signature with no detectable background at clinical field strengths. Perfluorocarbon core nanoparticles (PFC NP) are a class of clinically approved emulsion agents recently applied in vivo for ligand-targeted molecular imaging. The objective of this chapter is to outline a multinuclear 1H/19F MRI protocol for functional kidney imaging in rodents for mapping of renal blood volume and oxygenation (pO2) in renal disease models.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This experimental protocol chapter is complemented by a separate chapter describing the basic concept of functional imaging using fluorine (19F) MR methods.

Quantitative MRI adds to neuropsychiatric lupus diagnostics.

Attributing neuropsychiatric manifestations to SLE is often challenging. Brain white matter lesions are frequent in SLE at MRI, but their diagnostic role is unclear. Here, we assessed whether white matter lesions count, volume and distribution measurement can help in the diagnosis of neuropsychiatric systemic lupus erythematosus (NPSLE). Brain dual-echo and 3D T1-weighted sequences were acquired from 32 patients with SLE and 32 healthy controls with a 3 T-scanner and employed to derive T2-hyperintense lesion volume (T2LV), number (T2LN) and probability maps (LPM) using a semi-automatic local thresholding segmentation technique. NPSLE was classified as per the ACR nomenclature, the Italian Society for Rheumatology algorithm and by clinical impression. Clinical descriptors including the SLE International Collaborating Clinics/ACR damage index (SDI) were also recorded. Higher T2LV were observed in SLE vs healthy controls (P<0.001) and in NPSLE vs other SLE (P=0.006). Patients with NPSLE also had higher T2LN (P=0.003) compared with other SLE. In SLE, T2LPM revealed a high prevalence of lesions in the splenium of the corpus callosum, right superior longitudinal fasciculus and right corona radiata. T2LV and T2LN correlated with SLE duration (rho = 0.606; P<0.001 and rho = 0.483; P=0.005, respectively) and age (rho = 0.478; P=0.006 and rho = 0.362; P = 0.042, respectively). T2LV also correlated with SDI (rho = 0.352; P=0.048). SLE patients with fatigue had lower T2LN (P=0.038) compared with patients without fatigue. Thresholds of T2LV ≥ 0.423 cm3 or of T2LN ≥ 12 were associated with definite NPSLE and improved the classification of patients with possible NPSLE per clinical impression. Brain white matter lesions (WML) quantitation adds to NPSLE diagnostics.